Water-dispersible monoazo dyestuffs



3 344 133 WATER-DISPERSIBLit MoNoAzo DYESTUFF Werner Bossard, Riehen, and Francois Favre, Basel,

Switzerland, assignors to J. R. Geigy A.G., Basel, Switzerland No Drawing. Continuation of application Ser. No.

136,163, Sept. 6, 1961. This application Sept. 20, 1963, Ser. No. 310,456

Claims priority, application Switzerland, Sept. 11, 1959, 78,083/59; Feb. 28, 1961, 2,399/ 61 7 Claims. (Cl. 260163) This application is a continuation of our copending application Ser. No. 136,163, filed on Sept. 6, 1961 as a continuation-in-part of our application Ser. No. 54,362, filed on Sept. 7, 1960, both now abandoned.

The invention concerns new, difiicultly water soluble monoazo dyestuffs which are dispersible in water, processes for the production thereof, dyeing processes using the new dyestuffs and, as industrial product, the material dyed by the aid of these dyestuffs.

It has been found that new, valuable monoazo dyestuffs which are difiicultly soluble in water are obtained by reacting an isocyclic diazonium compound with a aminopyrazole coupling in the 4-position, the components being so chosen that the dyestuff contains neither water solubilizing groups which dissociate acid in water nor an aromatically bound hydroxyl group.

As isocyclic diazonium compounds, those of the naphthalene and, preferably, of the benzene series are used.

As defined, the diazo components should not contain any sulfonic acid, carboxylic acid groups or aromatically bound hydroxyl groups. The isocyclic radicals thereof can otherwise be substituted as desired, for example by hydrocarbon groups such as methyl, ethyl, isopropyl, tert. butyl, tert. amyl, cyclohexyl phenyl, benzyl groups; by ether groups such phenoxy, cresoxy, chlorophenoxy, phenylthio, p-chlorophenylthio groups; by acylamino groups such as the acetylamino, chloroacetylamino, B-chloropropionylamino, methylsulfonylamino, chloromethylsulfonylamino, benzoylamino, chlorobenzoylamino groups; by amino groups such as dimethylamino, diethylamino, bis-cyanoethylamino, phenylalkylamino groups, in particular, however, by electrophilic substituents such as the nitro group, the cyano group, the halogens fluorine, chlorine and bromine, the keto group, the sulphonyl group such as the methylor ethylsulfonyl butylsulfonyl, phenylsulfonyl, toluylsulfonyl, xylylsulfonyl, chlorophenysulfonyl, fluorosulfonyl groups, by sulfonic acid amide groups such as the sulfonic acid dimethylamide, diethylamide, dibutylamide, cyclohexylamide, phenylalkylamide, piperidide and morpholide groups.

The coupling components used according to the invention correspond to the tautomeric Formulas I and II lm s ll HzN \N/N HN wherein as methoxy, ethoxy, Z-hydroxyethoxy,

3,344,133 Patented Sept. 26, 1967 Nucleophilic substituents are preferreed as non-iono-.

genic substituents of phenyl radicals of the coupling components, for example, low alkyl groups, low molecular alkylether or phenyl ether groups, acylamino groups such as the acetylamino, the methylsulphonylamino group.

The coupling is performed advantageously in'an acid medium, in particular in a mineral acid to Weakly acid aqueous solution, possibly while gradually buffering the mineral acid, for example, with alkali metal salts of low fatty acids.

Monoazo dyestuffs which are free from sulphonic acid, carboxylic acid and aromatically bound hydroxyl groups are the subject, therefore, of the present application. These dyestuffs correspond to the general formula r wherein:

Arepresents at most bicyclic carbocyclic aryl radical,

R represents a member selected from the group consisting of lower alkyl and phenyl radicals,

R represents a member selected from the group consisting of hydrogen, aliphatic, cycloaliphatic, phenyl-lower alkyl, phenyl-lower hydroxyalkyl, and mononuclear carbocyclic aryl radicals.

lower alkyl lower alkyl -5 OiN S O 2N ower alkyl lower hydroxyalkyl and lower alkyl S OzN aryl In the above formula R is preferably the methyl group.

Preferred aliphatic radicals as R are lower alkyl radicals which can be substituted by the hydroxy or cyano group. If R is a cycloaliphatic radical, then it is advantageously the cyclohexyl or methyl cyclohexyl group. If R is a phenyl-lower alkyl radical, then it is advantageously the benzyl ora-phenylethyl group. If R is a phenyllower hydroxyalkyl radical, then it is advantageously the ,B-hydroxy-fl-phenyl-ethyl group. If R is a mononuclear .aryl radical, then it is advantageously an unsubstituted phenyl radical or a phenyl radical substituted by lower alkyl e.g. methyl, lower alkoxy, halogen e.g. chlorine and bromine, phenoxy, amino, acylamino, lower alkylsulphonyl or sulphonic acid amide groups, e.g. SO NH SO NH-lower alkyl, -SO NH-lower hydroxyalkyl,

lower alkyl -s om lower alkyl lower alkyl lower alkyl' 'SO2N and SOzN lower hydroxyalkyl aryl A particularly valuable class of compounds according to the invention corresponds to the formula and, depending on their composition, they produce on these fibres yellow, orange to red dyeings which have good fastness to wet, sublimation and light.

The following examples illustrate the invention. Where 5 not otherwise stated, parts are given as parts by weight. I H Il it The temperatures are in degrees centigrade. The relation- 2 ship of parts by weight to parts by volume is as that of f grammes to cubic centimetres. Example 1 wherein: 18 3 parts of l-amino-2 4-dinitrobenzene in 30 parts of of X1 and one X stlapds forflm i grqup and the concentrated sulphuric acid are diazotised for 10 hours other tor an electrophilic substituent, in particular haloat in the usual Way with nitwsyl Sulphuric acid cop cyano or Sulphcnyl groljlps silch alkyl and responding to 6.9 parts of sodium nitrite. The diazonium aryl Sulphonyl groups and sfflphomc f amlde groups 15 salt soluton so obtained is added dropwise at 5 to a Y represents i Chlorme bmmme Gr methyl and solution of 14.9 parts of l-isopropyl-3-methyl-5-amino- R2 has the meamng gwen above pyrazole in 300 parts of glacial acetic acid and 500 parts The dyestuffs according to the invention are suitable of water. for the dyeing of hydrophobic synthetic textile fibres from The reaction mixture is buttered by the addition of aqueous dispersion, for example for the dyeing of cellu- 20 sodium acetate until the reaction is weakly acid to Congo lose acetate and cellulose triacetate and especially of high red paper whereupon it is stirred for 2 hours at room molecular esters of aromatic polycarboxylic acids with temperature. polyfunctional alcohols, in particular for the dyeing of The dyestutf formed is filtered off under suction, washed high molecular glycol terephthalates at high dyeing temneutral with diluted sodium carbonate solution and dried peratures. They can also be used, however, for the dyeing at 60. It precipitatess in the form of an orange-red powof polyamide fibres such as nylon and of Perlon. der which, when milled with alkyl benzene sulphonate, The dyeing of hydrophobic textile fibres in aqueous disdyes polyester fibres, possibly in the presence of colour persion of the dyestuffs according to the invention is carriers such as o-phenylphenol, in orange-red shades. performed advantageously at temperatures of over 100 The dyeings have excellent fastness to light and migration. C. under pressure. On dyeing at the boiling point of the If in the above example, equimolecular parts of the water, the presence of colour carriers in the dyebath is diazo components given in the following Table I are used recommended, for example, the presence of phenylphenol instead of the 18.3 parts of 1-amino-2,4-dinitrobenzene or of other known similar phenolic carriers. and the coupling components given are added thereto The dyestuffs according to the invention are distinunder the same conditions, then dyestuffs are obtained guished by a surprisingly good affinity to hydrophobic which produce dyeings on polyester fibres having similar polyester fibres, in particular to polyglycol terephthalates good properties.

TABLE I Diazo component Coupling component Shade on polyster fibre 1-amino4-nitrobenzene III l-amino-fi-methyl-2,4-d1n1trobenzene 1-amino-2-chloro-4-nitrobenzene l-isopropyl-liquethyl-fi-aminopyrazole Yellow-Orange.

..do l-amlnoi-benzoylbenzene l-amino-Z-cyano-4-n.itrobenzene .do -amino-2-nitrobeuzene-4 suli0nic acid-N-methyl- N- henylamide.

-do min0-2-nitro-4-methylsulfonyl benzene. l-amino-Z, i dimtrob enzene 1- (fl-hydroxyethyl) -3-methyl-5-aminopyr ole. D 1,3-dimethyl-5-aminopyrazole Do. 1-methyl-3-phenyl-5-aminopyrazole. Do. 1 ethyl-3-1nethy1-5-aminopyrazole Do. 1-(6-methyl-cyclohexyl)-3-methy1-5-amin razole. Reddish orange. l-isopropyl-3-methyl-5-aminopyrazolo Orange.

1 (B-cyanoethyl) -3-metl1y1-5-aminopyrazole- Red-orange. 1-(a-phenylethyl)-3-methyl-5-aminopyrazole- Orange. 1-rnothyl-3-phenyl-5-amin0-pyrazole Do. 1,3-dimethyl-5-aminopyrazole Do. l-isopropy1-3-methyl-5aminopyrazole Yellow-orange. l-(B-hydroxyethyl)-3-methyl 5-aminopyrazol Do. 1-(B-eyanoethyl)-3-methyl-5-aminopyrazole Red-orange. l-mothyl-dphenyl-fiaminopyrazole Orange.

1-eth3 l-3-methyl-5-aminopyrazole, Do. 1-isopropyl-3-methyl-4-aminopyrazole.- Do. 1-(B-eyanoethyl)-3-methyl-5-aminopyrazole Do.

1, 3'dimethyl-fi-aminopyrazole Do. Lmethyl-S-phenyl-fi-arninopyrazole Do. 1-ethyl-3methyl5-aminopyrazole D 1-isopropyl-3-methyl-S-aminopyrazole 1-cyclohexyl-3-methyl-fi-amlno-pyrazole o. Yellow-orange. Orange-red.

l-benzyl-Ii-methyl5-aminopyrazole l-benzyl-3-methyl-5-aminopyrazole 1- (4onethyLcycloheXyD-K-methyI-SPaminopyrazo e.

. Yellowlsh-orange.

Orange.

Example 2 A fine suspension of 13.8 parts of 1-amino-4-nitrobenzene in 220 parts of water and 26 parts of 36% hydrochloric acid is diazotised at 5 to 7 in the usual way by the addition of 6.9 parts of sodium nitrite.

The clear diazo solution is added dropwise to a solution of 16.1 parts of 1-phenyl-3-methyl-5-aminopyrazole in 300 parts of glacial acetic acid and 500 parts of water; After 1 hour, the reaction mass is buffered with sodium acetate to a pH of 4 to 4.5.

The precipitated dyestulf is filtered off, washed neutral with sodium carbonate solution and dried at 55 to TAB LE Diazo component 60. It is a red-orange powder and it dyes polyester fibers, after milling with alkylarylbenzene sulphonate and possible with the addition of colour carriers, from aqueous dispersion in yellow-orange shades. The dyeings have very good fastness to light, perspiration and migration.

If in the above example instead of the 13.8 parts of 1-amino-4-nitrobenzene, a corresponding amount of the diazo components given in the following Table II are used and the coupling components given are added thereto under the same conditions, then dyestuffs are obtained which produce dyeings on polyester fibres which have equally good proper-ties.

Coupling component Shade on polyester fiber l-amlno-2,4-dinitrobenzene 1-pheny1-3-methyl-5-arninopyrazole Orange-scarlet.

1- (4'- meth ylphenyl)-3-rnethyl-5-a.minopyrazole Orange. 1,3-diphenyl-5-aminopyrazole Do. 1-phenyl-3-methyl-5-aminopyrazole. Red-orange. 1'(41-acetylamin0phenyl)-3-methyl-5-amlnopyra- D0.

20 e. 1-(2f4-dlmethylphenyl)-3-methy1-5-aminopyra- Do.

20 e. 1-(3-methoxyphenyl)-3-methyl-5-aminopyrazole.. Do. 1-(2'-rnetl1ylphenyl)-3methyl-5-arninopyrazole Do. 1-phenyl-3-methyl-5-aminopyrazole Yellow. 1-(4-aminopheny1)-3-methyl-5-aminopyrazole Do. -(3-methy1pheny1)-3-rnethy15-aminopyrazo1e" Do. l-pheny1-3-metl1yl'5-aminopyrazole Orange. 1- (4- ethoxyphenyl)-3-rnethyl-5-aminopyrazo1e Do. do 1,3-d1phenyl-fi-aminopyrazole Do. mino-4-phenylsulpho y -n1trobenzene l-phenyl-3-Inethyl-5-aminopyrazole Do. do 1-( -methylphenyl)-3-methyl-5-aminopyrazo1e D0. 3 'd 1-(2-rnethoxy-5-methylphenyl)-3-methyl-5- D0.

aminopyrazole. 1-phenyl-3-methyl-5-aminopyrazole Yellow-orange. 1-(4-metl1ylphenyl)-3methyl5-aminopyrazole Do. 1- (3 -methoxyphenyl) -3-Inethyl-5-amin0pyrazole Do.

o 1-amino-6-bromo-2,4-dinitrobenzene o do. 1-are;no-2,5-dich1oro-4-nitrobenzene pyrazo benzene.

1-phenyl-3-methyl-5 1-(2',6-dimethylphenyl)-3methyl-5-amin0 -amin0pyrazole. -aminopyrazoleaminopyrazole ylphenyl)-3-methyl-5-aminopyrazoleoxyphenyl)-3-methyl-5-aminopyrazole.

-amin0pyrazole do 1-(4 ethoriyphenyl)-3-rnethyl-fi-aminopyrazola. Lam o-2-cyano4-nitrobenzene l-phenyl-3-methyI-S-aminopyrazole. L o 1-(2-methylphenyl)-3-methyl-5-aminopyrazole D 1-(4-methy1phenyl)-3-methyl-5-aminopyrazole. Do. l-amrno-Mzarboethoxybenzene 1-pheny1-3-methyl-5-aminopyrazole Yellow. l-(4'-methoxypheny1)-3-1nethyl-5-aminopyrazole. D o. o 1-(2-Inethylphenyl)-3-Inethyl-5-aminopyrazole Do. l-amino-Z-oarb0ethoxy-4-nitrobenzene l-phenyl3-methyl-5-arninopyrazole Orange 1-emino-2A-djnitrobenzene 1-pheny1-3-ethyl-fi-aminopyrazole Reddish orange. l-amino-2-nitro-4-methylsulphonylbenzene l-phenyl-3-ethyl-5-aminopyrazole Yellowish orange. 1-amino-2-nitro-4-methylsulphonylbenzenel-phe11y1-3-n-propyl-5 aminopyrazole Do. 1-amlno 6-methyl-2,4-dinitrob enzene l-phenyl-3-methyl-5aminopyraz ole Orange. 1-amh1o-2,4-dinitrobenzene 1-(4-ethoxyphenyl)-3-rnethyl-5-aminopyrazole Reddish orange. 1-amino-2 nitro-4-ethylsulphonylbenzene. l-phenyl-B-methyl-5-aminopyrazole Do. 1-amino-2-chloro-4-nitrobenzene 1- (4-ehlorophenyl) -3-methyl-5-aminopyrazole Do. 1-amino-2-ehloroA-nitrobenzene l-(2-chl0f0-6-methylphenyl)-3-methyl-5-amino- D0.

pyrazo e.

do 1-(2,%-dichl0rophenyl) -3-methy1-5-aminopyr- Do.

i azo e. V 1-amino-2, 6-diehloro-4-nitrobenzene. 1-(3,4-dichlorophenyl)-3-methyl-5-aminopyrazole D0.

do l 1- (3-s1ulphamidophenyl)-3-rnethyl-5-aminopyr- Do.

azo e. do 1-(4-S1l1lphamid0phenyl)-3-methyl-5-ami11opyr- Do.

azo e. i,

. do v 1-(3-N-methylsylphamidophenyl)-3-methyl-5- Do.

aminopyrazole.

do 1-(3-N-dimethylsulphamidophenyl)-3-methy1-5- Do.

. amlnopyrazole. I l-amino-4-nitrobenzene 1-(3-N-diethylsulphamidophenyl)-3-methyl-5- Red orange.

- aminopyrazole.

do 1-(3-N-ethylsu1phamidophenyl)-3-methyl-5 Do.

amrnopyrazole. 1-amino-2, 4-dinitrobenzen l-(4-phenoxyphenyl)-3methyl-5-aminopyrazole Do. 1-amino-2-ehloro4-nitrobenz 1-(4'-phenyoxyphenyl)-3-methyl-5-aminopyrazole Yellow orange. l-amino-Z, 6-diehloro-4-nitrobenzen 1-(3-N-fl-hydroxyethylsulpharnjdophenyl)-3- D0.

fiaminopyrazole. 1-amino-2, 4-dinitrobenzene do Do. l-amiuoA-benzoylbenzena l-phenyl-3-methyl-5-arninopyrazole D0. 1-amino-2, 4-dinitrobenzene l-(4-a1ninophenyl)T3-methyl-fi-aminopyrazole Red orange. 1-amino-4-nitrobenzene 1-(4-brom0phenyl)-3-methy1-5-arninopyrazole Orange. 1-amino2-nitro-4ethylsulfonylbenzen d0 Yellowish red.

do l-isopropyl-3-methyl-fi-aminopyrazole Do. l-amin y 1-(4-ethoxyphenyl) -3methyl-5-a1ninopyrazole- Do. l-aminomtro 4-Nethylsulpham1dophenyl 1(4chlorophenyl)-3-rnethyl-5 arninopyrazole D0. l-amino-Z-nitr0-4-sulphamid0benze11e l-phenyl-3-methyI-S-aminopyrazole Do.

.do l-iSopropy1-3-methyl-5-aminopyrazole. Do. l-arnino-2-nitro-4-N-diethylsulpharnidobenzene l-(4'-chloropheny1)-8'methyl-5-arnin0pyrazole Do. l-amino-2nitro-4-N-dimethylsulpharnidobenzene 1-isopr0pyl-3-methyl-fi-arninopyrazole Do. l-amino-Q-nitro-4-diethylmethyl-N-B-hydroxy- 1-(4-ethoxyphenyl)-3-methyl-5-aminopyrazole Do.

ethylsulphamiclobenzene. 1-amino-2-nitro-4-N -methyl-N-pheny1sulphamidol-pheny1-3-methyl-E-amlnopyrazole Do.

TABLE II-Continued N 0. Diazo component Coupling component Shade on polyester fiber 73 1amino-2,4-dinitrobenzene l-(4'onetirylsulphonylphenyl)dmethyl-fi-amiuo- Reddish orange.

pyrazo e. 74 .do 1-(3"methylsulphonyl-6-methylpheny1)-3-methyl- Do.

arninopyrazole. 75 1-amino-2,4-dinitrobenzene 1-( ethfilsulphonylphenyl)-3-mcthyl-S-amino Do.

pyrazo e. 76 1-amino-2-nitro-4-acetylbenzene l-phenyl-3-methyl-5-arninopyrazole D0. 77 o 1-isopropyl-3-methyl-5amin0pyrazole Do. 78 l-a-mino-2chloro-4-nitrobenzene 1-(4'-isopropylsulphonylphcnyl)3-methyl-5- Orange.

aminopyrazolc. 79 l-am1no-2,6-dichloro-4-nitrobenzene 1-(4-n-biitylsulphonylphenyl)-3-methyl-5-amino- D0.

pyrazo e. 80 do 1-(4-N-isopropylsulphamidophenyl)-3methy1-5- Yellow orange.

aminopyrazole. 81 do 1-(4'-N-diisopropylsulphamidophenyl)-3-methyl- Do.

5-aminopyrazole. 1-(4-N-ethylphenylsulphamidophenyl)-3-methyl- Do.

5-aminopyrazole. d0 1-(3'-N-methyl-N-B-hydroxyethylsulpharnido- Do.

l-anainofij-diet hoxy-l-nitrobenzene 0 1-amino-2-nitrobenzcne+sulphonic acid-N-isopropylamide.

Reddish orange.

o. Yellowish orange.

l-amino-Z-m'trobenzene-tsulphonic aeid-N-diisopropylamide. l-amino-lnitrobenzene-t-sulphonic acid-N-nbutylamide. l-amino-Z-nitrobenzene-i-sulphonic acid-N-ethyl- N-phenylamide. l-amino-Z-nitroben;ene-4-sulphonic acid-N-B- do D0.

1-isopropyl-3-methyl-5-aminopyrazole Do.

1- (4'-chlorophenyl)-3-methyl-5 aminopyrazole Do.

. do Do.

hydroxyethylarnrde.

Example 3 Nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite, is added to 20.7 parts of 1amino-2,6-dichloro-4-nitrobenzene in 40 parts of concentrated sulphuric acid, and diazotising is performed within 1%. hours at 25. The diazonium salt solution, which has possibly been clarified, is poured into a cooled solution of 9.6 parts of B-methyl-S-aminopyrazole in dilute hydrochloric acid and the reaction mass is brought to a pH of 4 to 4.5 by the addition of sodium acetate. The precipitated dyestulf is filtered off, washed neutral with dilute sodium carbonate solution and water and dried at 60. A scarlet powder is obtained which is milled with fatty alcohol sulphonate and which dyes polyester fibres from aqueous dispersion in vidid orange shades. The dyein gs are distinguished by good fastness properties.

It in the above example, instead of the 20.7 parts of 1- amino-2,6-dichloro-4-nitrobenzene, equimolar amounts of the diazo components given in the following Table III are used and they are coupled under the same conditions with the same amount of 3-methyl-5-aminopyrazole, then dyestuffs are obtained which produce dyeings having similar good properties on polyester fibres.

18.3 parts of 1-amino-2,4-dinitrobenzene are dissolved in parts of concentrated sulphuric acid and diazotised at 15 for 10 hours with nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite. The solution of the diazonium compound is added dropwise at 5 to a solution of 21.7 parts of 1(fl-hydroxy-B-phenylethyl)- 3-methyl-5-aminopyrazole in 400 parts of glacial acetic acid and 600 parts of water.

The mixture is buffered with sodium acetate until the reaction is weakly acid to Cong-o paper. The precipitated dyestutt is filtered off, washed with water and dried at 60. In this way, a red powder is obtained which, when milled with a synthetic dispersing agent, dyes polyester fibres such as Dacron from aqueous dispersion with the addition of swelling agents in vivid orange shades. The dyeings are distinguished by very good fastness to light and migration.

The coupling component used in the above example can be obtained by reacting styrene oxide with hydrazine in molar ratio of about 1:1 and then condensing the 5- hydroxy-p-phenyl-ethyl hydrazine obtained with cyanoacetone imine.

Example 5 23 parts of 1-amino-2-nitro-4-ethylsulfonylbenzene in 40 parts of sulphuric acid are diazotised for 10 hours at 15 with nitrosyl sulphuric acid corresponding to 6.9 parts of sodium nitrite.

The solution of the diazonium compound is added dropwise at 5 to a solution of 21.7 parts of l-(B-hydroxy B-phenylethyl)-3-methyl5-aminopyrazole in 400 parts of glacial acetic acid and 600 parts of water. The reaction mixture is then buffered with sodium acetate to a pH of 4-4.5.

The red-orange dyestufl which precipitates is filtered off, washed with Water and dried at 60.

After milling with an alkali alkyl-arylbenzene sulphonate, it dyes polyester fibers in yellow-orange shades. The dyeings have excellent fas'tness to sublimation.

If in the above example, instead of 21.7 parts of l- (5 hydroxy fl-phenylethyl)-3-methy1-5-aminopyrazole, 23.1 parts of 1-(5 hydroxy-B-phenylethyl)-3-ethyl-5- aminopyrazole or 27.9 parts of l-(fi-hydroxy-o-phe'nylethyl)-3-phenyl-5-aminopyrazole are used as coupling component, then dyestuffs having similar properties are obtained.

Example 6 13.8 parts of 1-amino-4-nitrobenzene are suspended in parts of water and 26 parts of 36% hydrochloric acid and diazotised by the addition of 5-7 of 6.9 parts of sodium nitrite.

The clear solution of the diazonium compound is added dropwise while stirring to a solution of 21.7 parts of 1 (B hydroxy-{i-phenylethyl)-3-methyl-5-aminopyrazole in 350 parts of glacial acetic acid and 500 parts 9 v v of water. After 1 /2 hours, the pH of the reaction mixture is adjusted to 4 with sodium acetate.

The precipitated dyestuff is filtered off, washed neutral with water and dried at 55-60". It is a red-orange powder. When milled with an alkali alkyl-arylbenzene sulphonate it dyes polyester fibers from aqueous dispersion, possibly with the addition of swelling agents, in orange shades. The dyeings have very good fastness to light and migration.

If in the above examples, instead of 1-amino-4nitrobenzene, 17.25 parts of 1-amino-2-chloro-4-nitrobenzene are used, then a dyestuff having similar properties 'is obtained.

' Example 7 21.7 parts of 1-amino-2-nitrobenzene-4-sulphonic acid amide are diazotised in the usual way for hours at in 30 parts of concentrated sulphuric acid with nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite. The solution of the diazonium compound obtained is added dropwise at 50 while stirring to a solution of 21.7 parts of 1-(fi-hydroxy-fl-phenylethyl)-3- methyl-S-aminopyrazole in 300 parts of glacial acetic acid and 500 parts of water.

The acid reaction of the reaction mixture is bufiered by the addition of sodium acetate until Congo red paper is only slightly turned blue whereupon the whole is stirred for 2 hours at room temperature.

The dyestuff formed is filtered off under suction, washed with dilute sodium carbonate solution until the washing water is neutral and dried at 60. It precipitates in the form of a yellow-orange powder which, when milled with sodium dodecyl benzene sulphonate, dyes terephthalic acid polyester fibres from aqueous dispersion, possibly in the presence of a swelling agent such as o-phenylphenol, in yellow-orange shades. The dyeings have excellent fastness to light and migration.

Example 8 20.7 parts of 1-amino-2,6-dichloro-4-nitrobenzene are dissolved in 40 parts of concentrated sulphuric acid and nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite, is added. Diazotisation is performed, with stirring, for 1 hours at 25. The solution of the diazonium compound, after possible clarification, is poured, while stirring, into a cooled solution of 21.7 parts of l -(;8 hydroxy B phenylethyl)-3-methyl-5-aminopyrazole in dilute hydrochloric acid and the pH of the reaction mass is adjusted to 4-4.5 by the addition of sodium acetate. The precipitated dyestutf is filtered off, washed neutral with dilute sodium carbonate solution and with water and dried at 60. In this way an orange powder is obtained which is milled with fatty alcohol sulphonate. It dyes polyester fibres from aqueous dispersion in vivid orange shades. The dyeings are distinguished by good fastness properties.

We claim: 1. A monoazo dyestutf of the formula Y X1 N=NC CRi X, H2N(HJ\ /1Q' N i. wherein:

of X and X one X stands for the nitro group and the other for an electr'ophilic substit-uent selected from the group consisting of nitro, cyano, chloro, bromo, benzoyl, carboethoxy,

lower alkyl-sulfonyl with lower alkyl of 1 to 4 carbon atoms, phenylsulfonyl, toluylsulfonyl, chlorophenylsulfonyl, monoand di-lower alkyl-sulfamido, cyclohexylsulfamido, N-phenyl-N-methyl-sulfamido,

N phenyl-N-ethyhsulfamido, N-hydroxyethyl-sulfamido, N-methyl-N-hydroxyethyl-sulfamido;

Y is a member'selected from the group consisting of hydrogen, chlorine, bromine and methyl;

R is a member selected from the group consisting of lower alkyl with 1 to 3 carbon atoms and phenyl, and

R is a member selected from the group consisting of hydrogen, lower alkyl, hydroxy-lower alkyl, cyanolower alkyl, cycloalkyl with 6 to 7 carbon atoms, phenyl-lower alkyl, phenyl-lower hydroalkyl, phenyl, methylphenyl, loweralkoxyphenyl, chlorophenyl, phenoxyphenyl, anilino, lower alkyl-sulfonyl-phenyl, -phenyl-S0 -NH -phenyl-SO NH-lower alkyl, -phenyl-SO NH- (hydroxy-lower alkyl),

lower alkyl -phenyl-S02N lower alkyl lower alkyl -phenyl-SO -N (hydroxy-lower alkyl and lower alkyl -phenyl-S 01- phenyl 2. The monoazo dyestulf of the formula 3. The monoazo dyestufi of the formula I on,

I HO-CH 4. The monoazo dyestutf of the formula HsCz-SOr-O 5. The monoazo dyest'ufE of the formula 7. The monoazo dyestufi of the formula References Cited UNITED STATES PATENTS 15 2,728,762 12/1955 Heyna et a1. 260-163 3,012,843 12/1961 Gang-meux et a1. 260-163 X 3,144,437 8/1964 Uehlinger 260-162 X CHARLES B. PARKER, Primary Examiner.

D. M. PAPUGA, Assistant Examiner. 

1. A MONOAZO DYESTUFF OF THE FORMULA 